The present invention pertains to an immersible molten metal sampling device and particularly to one which includes a pair of coaxial tubes made of a vitreous material.
There exists a variety of molten metal sampling devices which are immersed in a molten metal bath for example in a steel manufacturing process such that a sample of the melt can be taken to determine the contents of the melt during the steel manufacturing process. U.S. Pat. No. 4,445,390 discloses a sampling device for the removal of a sample from a molten metal bath to capture the total hydrogen content of a sample. In this and other metallic evacuated tube samplers however, the molten metal bonds to the metallic wall surfaces of the sampler and when the solid sample is analyzed therefor the resulting pin-shaped sample includes not only the molten metal desired to be analyzed but also a portion of the sampling device itself.
Glass tube samplers have been employed in the past and typically constitute a single evacuated glass tube which is immersed into the molten bath and subsequently removed and chilled first in a water bath and subsequently in liquid nitrogen in order to prevent the escape of hydrogen from the sample. Inasmuch as it is necessary to relatively rapidly chill the sample to prevent the escape of hydrogen it is necessary to quickly remove the sampling device from the sample holding tube. In the past this has been very difficult inasmuch as typically the tube is encapsulated in a ceramic material which is part of a holder as shown for example in U.S. Pat. No. 3,369,406. Naturally the longer it takes to remove the sampling device from the holder for chilling, the more free hydrogen can escape and the accuracy of the resulting analysis of the sample is adversely affected.